The Lions' primary staff is now complete, though they could still add a quarterbacks coach. It's unclear if they will, however, given the experience of head coach Jim Caldwell and offensive coordinator Joe Lombardi at the position.

Other positions, such as quality control assistants, still are expected to be filled.

Caldwell said this week he believed he could hire a receivers coach who would help star Calvin Johnson become even better.

"The good thing is he always wants to get better. He's a worker," Caldwell said of Johnson. "I think when a guy has that kind of attitude, he'll find a way. Getting better in this league sometimes is only about 'that much' of a difference.

"He's a great, great player, right? But the great ones are the ones who are looking for that edge, and he's one of those individuals. I think we can certainly have a guy in place that will certainly help him attain his goals."

Robert Prince -- not to be confused with new tight end/assistant head coach Ron Prince -- spent the past two seasons as the Broncos' offensive coordinator. They ranked 68th in total offense in 2012, but jumped to 20th last season.

Prince worked with Boise State's receivers in 2011, and also has NFL experience at the position. He was the Atlanta Falcons' receivers coach from 2004-06, then became the assistant receivers coach for Jacksonville from 2007-08 and the receivers coach for Seattle in 2009.

He returned to college in 2010, first becoming Colorado's passing game coordinator and receivers coach in 2010 before heading to Boise State.